Radium luminous article and method of producing same



RADIUM LUMINOUS ARTISLE AND METHGD 0F FREQ USING SAME.

APPLICATEGN mm) 05mm. 1919.

Pate/M65. $2111. EL 1921.

WHEN/M iu/wuvous CoMPoulvn 5 f/WMELED SURF/HIE firm/0M a wwmou Comwmww INvENr-m:

NITED. STATES PATENT OFFICE.

ELIQT OHAIRA, 0F WALTHAM, MASSACHUSETTS.

imnmrr'nummous nnrrcrn AND mn'riron or rnonucme snun Specification of Letters Patent.

Patented Jan. 11, 1921.

Application filed December 26, 1919. Serial No. 347,592.

To all whom it may concern:

Be it known that I, ELIOT OHARA, a citi-.

particular portions of dials, signs and other articles for the purpose of retaining self- .luminous in the dark the particular por tions of the article which have been treated with the radium luminous material. The radium compound is usuall purchased in the form of a powder. retofore' the method usually employed to applythe radium luminous compound to the surface of the article has been through the medium of a gum, varnish, glue or other adhesive, which later dries in the same way. as any paint or varnish. When it is put on in thisold way the luminous coating is not weatherproof or .acidproof, and will soil easily, and

' if the dial iscleaned with alcohol or benzin itwill remove the luminous characters. The object of my invention is'to provide a new method of applying a radium luminous compound which will retain it weatherproof or acidproof, and will not easily soil, and such that when cleaned with alcohol or' benzin it will notremove the luminous charing{ 34 C0, 15CaQ H and .33MnO or other formulae given in 'Tkorpes Dictionary of actors. Luminosity has longer life as disintegrationor breaking up of zinc sulfid crystals is delayed and one object of the invention is to prevent such disintegration.

The invention will be "fully understood from the following description when taken in connection with'the accompanying drawings, and the novel features will be pointed out and clearly defined inthe claims at the close of this specification.

; I In the drawings, Figure l'is a view-sh0wing in a greatly exaggerated scale the article to be treated with the luminous material, and showing the mixture of radium luminous material and flux applied thereto'before being heated.-

-F g. 2 shows the same article and compound after it hasbeen heated.

Referring now to the drawings, the article 3 is provided with an enameledsurface 5. A flux or. glaze" reipresented by the black grains 1,-which pre erably should contain able for this purpose.

no lead is prepared by grinding it to about the same size grain or perhaps finer than the crystals of zinc sulfid powder in the radium compound. I then mix substantially equal proportions of the flux thus 'prepared and powdered radium luminous compound represented by the white grains 2. Inmixing the two ingredients it is important not to grind them but simply to stir. them lightly together, because any grinding breaks the crystals of zinc sulfid in the radium luminous compound, and only when the crystals are complete is the best luminosity possible.

One kind of radium luminous compound suitable for such purposes consists of crys tallized zinc sulfid mixed in proper proportions with radium bromid; another suitable compound consists of zinc sulfid mixed with mesothorium. A suitable proportion is two parts of radium bromid or mesothorium to ten thousand parts of zinc sulfid, but these."

proportions may be varied considerably if esired. There are, however, numerous other compounds which may be employed with good results and which contain radio-active and radio-responsive material which will stand the temperature of glazing, and I consider any such compound-as coming within the scope of my invention. Any one of certain types of potash-lime glass which is free from lead makes a suitable flux or glaze such for instance as a glass made accordto the following formula: S0

radium compound and the leadles's fiux'or'; glaze are about half and half I do not limit myself to the use of equal. proportions al- '105 though I consider that the best results are obtained by making the proportions equal."

This mixture of the radium compound and the leadless laze is then made into a ice paste by the addition'of a little water or 1 volatile oil as preferred, and the paste is then applied to the enameled surface of the dial, or other article 3. Then'the whole heit.

dial orsign is fired in a mufllefurnace at, a temperature of from 1000 to 1200 Fahren- The glaze vitrifies and fills up the space between the crystals of radium compound so that each crystal is inclosed in the glaze 4 and the crystals 2 are separated from each other by the intervening glaze, and all the crystals are held solidly in place Within the glaze. See Fig. 2. By means of this inclosing glaze, the crystals of radium compound are prevented from disintegrating or splitting apart. 'Disintegration impairs the luminosity. Theglaze is impervious to gasoilene and to most acids, and is absolutely weatherproof as well as transparent.

The radium luminous crystals are thusaffixed to the dial or other article in a manner that makes them very permanent and prolon s the luminous life.

1T0 gum or other-adhesive is required to cause the coatin to adhere to the article other than the se f-contained adhesive character of the glaze employed.

What I claim is 1. The method of applying radium luminous compound to a dial or other article consistin r of mixing the radium luminous compoun -with a flux or glaze, and making the mixture into a paste, then applying the paste to the surface of the article, and then firing the article in a mufile furnace at a very high tions of the article which are to be rendered luminous and then firing the article in a furnace at a high temperature suflici'ent to melt the glaze and cause it to surround each crystal of the radium compound, then allowing the article to cool and the glaze to harden.

3. The method of applying radium luminous compound to a dial or other article consisting of mixing together a powdered radium compound containing crystals of zinc sulfid wlth a glaze in such manner as to surround the crystals with the glaze, applying the mixture to the portions of the article which are to be rendered luminous, and then vitrifying the mixture upon the article. V

4. The method of making a radium luminous article, consisting of mixing together a radium luminous compound containing crystals of zinc sulfid with powdered glaze to form a paste, applying the pasty mixture to the surface of an article which is to be rendered luminous, then firing the mixture at a sufficiently high temperature to melt the glaze and cause it to surround the said crysr tals of zinc sulfid, and then allowing it to solidify.

5. A dial or other article having radium luminous markings vitrified thereon, consisting of radium luminous compound com? bined with a glaze thoroughly mixed therewith in such manner that the crystals con- 1 tained in the radium luminous compound are each surrounded by .the glaze, said mixture being vitrified upon the article to which it is attached and secured to the article by the glaze itself.

6. A dial or other article having a radium luminous coating containing zinc sulfid crystals surrounded by asolid transparent glaze.

In testimony whereof I afiix my signature.

ELIOT OHARA. 

